1. Field of the Invention
The present invention relates to gate valve assemblies in which the gate closure member reciprocates in a direction transverse to the stem axis.
2. Brief Description of Prior Art
Many valves have been taught in the prior art where the gate closure member has a sealing surface that wedges against the valve body seating surface in order to seal the fluid flow passageway, e.g. a tapered wedge gate valve, a tapered plug valve actuated by a Lift-and-Turn mechanism, an expanding wedge gate valve, etc.
A gate valve is generally understood to mean a valve in which the gate closure member reciprocates along the stem axis between the closed and open positions of the valve.
In a tapered wedge gate valve, a tapered wedge gate of solid cross section is wedged into like tapered valve body seats to sealingly close the fluid flow passageway. The tapered wedge gate is pulled away from the valve body seats along the stem axis in order to open the fluid flow passageway. In other words, the gate reciprocates along the stem axis between the open and closed positions of the valve and therefore sufficient space should be provided for in the valve body cavity for permitting the reciprocating movement of the gate along the stem axis. Since the gate is moved away from the valve body seats, the fluid flow passageway cannot be sealed from the valve body cavity in the valve open position. It is also well known that the stem packing around the stem is subject to more wear in a reciprocating stem than in a rotary stem.
So it would be advantageous to have a reciprocating gate valve that is actuated by a rotary stem, since the stem packing would last longer than in a valve actuated by a reciprocating stem.
A valve in which the gate reciprocates along the stem axis, requires plenty of space above the valve body in a vertical installation in order to accommodate the bonnet and the handwheel. This poses a big problem for vertical installations such valves in confines spaces. If the gate is made to reciprocate in a direction transverse to the stem axis, less vertical space will be needed above the valve body.